Quick look: Canon's new compressed Raw format

Canon's new entry-level EOS M50 is also the first Canon camera to come with the new Digic 8 processor, allowing it to capture smaller C-Raw files in the new CR3 format.

The EOS M50 may be aimed at beginning photographers, but its all-new Digic 8 processor makes it Canon's first camera to use the CR3 Raw file format. Older Canons that used the CR2 file format could capture either losslessly compressed Raw files or 'medium' and 'small' equivalents, both saving you disk space, the latter at the expense of reducing resolution.

However, if you enable the compact 'C-Raw' option on the M50, the files will be 30-40% smaller than their losslessly compressed equivalents without any reduction in resolution. But are there any other image quality penalties to pay? Let's take a look.

Base ISO

The above images were shot and processed using our standard studio testing procedure. Do you see any differences? We couldn't find any - but we decided to see if boosting the ISO value and using our low-light scene would turn anything else up, particularly in terms of shadow noise.

High ISO

Now that we've switched to our low light setup and boosted the ISO by seven stops, the images still appear all but identical, even in terms of noise levels. So far, it looks like it's best for you to go ahead and switch into C-Raw and save yourself some disk space.

But when we put the EOS M50 through our standard exposure latitude test, we did find some evidence of what sort of processing is happening in Canon's C-Raw files.

Pushed shadows

Our exposure latitude test involves exposing our studio scene with increasingly lower exposures, and then pushing them back to the correct brightness in Adobe Camera Raw. With many older sensors, you would see an abundance of noise being added by the camera, but today's sensors output files that are much more tolerant to this sort of manipulation.

Basically, after pushing the files, we look into the shadow regions to assess the exposure latitude (essentially the dynamic range) of the Raw files. And it's after underexposing the EOS M50 by four stops and then re-brightening, we start to see some clearer differences between the regular Raw files and their C-Raw equivalents.

The resulting pattern can be more difficult to remove or reduce than normal noise patterns, and is reminiscent of artifacts left behind from noise reduction algorithms that we've seen in the past.

At this time, we're optimistic that users of Canon's new Raw format can shoot in C-Raw without a noticeable impact on image quality.

But after all, this is a four-stop push. Depending on your shooting, this may indicate a slight dynamic range disadvantage to using C-Raw, but it's likely to remain an edge case for most users. And so we've decided to finish off with a more informal test in a more common situation. We wanted to see if processing out the two different Raw files would turn up different results for the gradient in a blue sky.

Blue skies and takeaways

Smooth gradients can often trip up compression algorithms, particularly in many cameras' JPEG engines, so we wanted to see if there was any noticeable difference when the EOS M50 compresses its Raw files. As with our un-pushed studio images, it's again impossible to tell which is the normal Raw file, and which is the C-Raw file. So what does this all mean?

Of course, we still have plenty of tests to run on the EOS M50, but at this time we're optimistic that users of Canon's new Raw format can safely shoot in C-Raw and save themselves valuable memory card and disk space without noticeable impact on image quality.

Note that all of the above images of our studio scene were processed in an identical manner to images in our studio scene widget, meaning there was no sharpening nor noise reduction added. Adjustments for the blue sky scene were limited to highlights, shadows, whites and blacks in Adobe Camera Raw, and sharpening and noise reduction were left to default levels.

My 2 cents?Yes, the differences are obvious. But if you don't need the full 24 MP you can trade in some resolution to compensate for the noise and artifacts and have the benefits of smaller files and still have the benefits of raw. And that's a fine choice to have.

Personally I would rather have my archive software deal with compression, or not. When it comes to burst shooting there could be obvious performance improvements since the bottleneck is usually flash write speeds. This would be the only really good reason to have it done in-camera IMHO, not for squeezing more shots on an SD card.

We will always search for and find some image that this compression will "destroy" and there will be a huge bashing thread to follow. Even if it is a bunch of bricks or a picture of a cat doing something cute. Even then it would need to be printed on a billboard to even have a hope of seeing the defect...

Looks brilliant. I can't understand people who claim that hdd are essentially free when there are obvious cost, complexity, space and heat issues from needing more hdds. This is a great innovation, well done Canon. I will consider this in future as the reduced hdd costs may offset (in my head) the subscription to Lightroom necessary (to me) for using the new cameras that support this format.

Depends on where the compressing happens. If it happens during the write to the card, it won't help the buffer. If as the image is captured, it might help. I rather suspect it is the former, and space savings is the only benefit.

It is unfortunate this new CR3 format doesn’t support Cropped Raw to push file size efficiency even further and speed up write times. We would have to wait another 10 or 20 years for Canon to introduce it with CR4 if we are lucky ! 🤯

How many angels can dance on the head of a pin? Sony faced a lot of heat for lossy RAW compression in its A7x cameras and others. Most of it was on principle. In fact, compression artifacts were only visible when pixel-peeping very high contrast edges in atypical/unusual scenes. The example I best remember was someone's image of sun coming through stained glass windows in a dark cathedral. But I never saw the issue in my own images and I continue to use Sony's lossy compressed RAW even now that they have made (much larger) uncompressed RAW files available....

No posterization issue. And they do (now) offer a lossless option for the II and later models. And again - the lossy artifacts were mainly only visible when bumping exposure after the fact by several stops (or worse) and even then only on contrasting areas such as stained glass, etc. -- This Canon compression looks ATROCIOUS by comparison. Seriously awful.

@arbux... yes, I know. I never said they, and it’s irrelevant. My point is that the lossy Sony RAW format is excellent, showing artifacts only in rare conditions and even then you have to pixel peep and know what to look for. So I expect Canon will come up with something at least equally good.

I own an RX100. I've seen it once or twice on high contrast transitions on its RAWs. I've downloaded RAWs from an A7 and an A7RII that demonstrated it as well. So, yes, I've witnessed it for myself. It's there. I wouldn't say it's that common, and I wouldn't say it's all that serious. In my opinion, it's about as serious as the contre-jour flare in the D750, which is to say, not so much, unless your shooting includes a lot of the conditions that bring it out.

Do you actually shoot with your camera, or do you just fondle it while trolling photo forums and staring at the Sony ad posters on your wall?

I don’t understand the raging debate here. Is this really a camera for users who will shoot and process raw files? From what I’ve read on dpReview and other sites, the M50 is targeted at what I would call “entry level enthusiasts”, which is how I would describe myself. I’m more interested in how the M50 feels in my hands, if my nose hits the display when looking through the EVF, how natural the colors look in AUTO mode, how easy the dials are to use, how intuitive the menu is, etc. And how those attributes compare to the Fuji X-T20, Sony a6300, Olympus M10 Mark III, and others.

We have a M100 and from time to time my wife (M100) and I (6D L lens) shoot similar scenes. a) the jpg off the M100 is better than the 6D'sb) in some situations, like artificial light, interior shots, RAW in 6D can be tweaked and produce better jpg than the M100 jpgc) for health reasons, I find the 6D way too heavy for long day use. Getting the M50 after 50 years of photography does not put me in the "entry level enthusiasts" d) I use Capture Pro and would expect the C Raw to render as good, if not better jpg than the Digic 8.

Given our high degree of satisfaction with the M100, considering the M50 makes sense for us, as we have already started buying m lenses.

Jboyer: That's interesting to hear. I based my statement above on what I have read about where the M50 fits in Canon's lineup. One article even said it was targeted at buyers who wanted to move up from smartphone cameras, but the M50 surely seems like more than that to me. I used Nikon SLR cameras for almost 30 years before jumping to point & shoot digital cameras and smartphones, and now I want to get a more capable, but lighweight, ILC. Good to hear about your confidence in the M50!

I'm one of several in my photo club who have in recent times found ourselves tired of bigger and heavier cameras. Some have moved completely from Nikon to Olympus or Sony. I bought a Canon SL1 three years ago as a stop gap while waiting for a "proper" (integral EVF) Canon mirrorless. I skipped the M5 but just bought the M50. Weight of my camera is a big deal to me, since I usually end up also carrying half of my wife's gear, which is all full size and mostly long lens stuff. I don't care that the M50 is called an entry level camera. So was the SL1, but I never encountered anything I couldn't do with that camera.

You can't even accept the fact that Canon made a new good feature that benefits a large user base, even with 100% proof by DPR.com?

The ability to have a middle ground between Jpeg and Raw file size, that's much much closer to RAW in actual IQ, is a huge feature and a huge upgrade for my personal shooting (Jpeg).

I wouldn't have imagined that resolution, lowlight, noise, texture would be so unaffected even in the ridiculously pushed HDR files, but here they are, almost identical for that massive space difference!

And for those saying it's either RAW or crap, just try to make some sense before forming an opinion. Why wouldn't retaining 90% of the sensor information be better than 50%, just because a 100% exists? It's a ridiculous notion. (and BTW nothing's 100% and each manufacturer cooks Raws in their own way)

Agreed. I have always shot RAW. But recently - now that I am starting to run out of places to put all of these files - I am considering still shooting RAW - but then processing to taste and then deleting all the RAWs. Just because they take up so much space. This new c-raw looks pretty good to me.

It can be either an upgrade for JPEG shooters like myself (in quality, to almost 95% raw) or an upgrade for raw shooters (in storage and speed, by 40%).

Has anyone downloaded the files or even just read the article? You cannot, cannot spot, any single image difference, from 100 to 12800 ISO. Nothing. And you save 40% size. Only when you push the specific shadows slider by more than 4-5 EV stops, you "may" see a difference at 1:1... and the "artefact/difference" doesn't even look bad! It's like some NR patch

I pushed the hell out of them and I can confidently say Canon could have passed the CR3 files as CR2s and no single user would complain about compression or IQ on the m50. Compressed RAW isn't new but it's truly impressive here. Other implementations, even like the infamous R3D cine raw are way worse than this. They show artefacts the moment any compression kicks in. at least posterization.

I shoot JPEG simply because I find my subjective choice over exposure and colour line up perfectly with Canon's slightly tweaked PPs. And because I have no method of printing or viewing 14bit of detail to audience. I was the head cheif colourist for a 42 episode highly cinematic TV series I can link, I can grade a DSLR's CR2 file. I just choose not to as I end up making the same choices made by the camera's JPEG engine.

It's only very rare when I want some over-done instagramish, high blacks, flares, screwed up colours, that I shoot RAW, just as an insurance.

Once you've worked for video a long time, you kind of hate on photographers. God, while you're buying 5-6K cinema cameras that shoot sub-JPEG compression where 8bit 4:2:0 24mbps is the norm, and you're required to grade that to make it very contrasty, vibrant, cinematic, clean, GOD! 14bit 444 6K CR3 files with 40% saving at THAT IQ and they complain!! That"s a new level!

if I were in DPR shoes, I'll do the same. Based on browsing photography forums. I 'bet that RAW shooters use either LR or the native RAW Application of the manufacturer.The LR becomes the lingua franca, and avoids disputing issues like my RAW processor is better than yours... Personally, I will take with a grain of salt any LR RAW processing, especially on new cameras, because it may not be optimized yet, if ever. You can use DPP if you want as the RAW files are available and pass your own judgement.

The point of raw is to maintain as much information as possible. If this is not a lossless compression then, by definition, you have lost some data. I don't see the point. Storage is (reletively) cheap so why throw away the very reason for shooting raw over jpeg in the first place?

@Ebrahim - looks like you're sacrificing image quality to me. The question is not if but how much. And it's up to the user to decide if that how much is too much. That pattern is ugly to me, so I probably wouldn't use it. I fail to see why this makes any sense. Hard drive space is the least of our worries.

@Ebrahim, if it is not lossless compression then you must be losing something and I would prefer not to lose anything. Especially as the only advantage is space, of which I have plenty and can cheaply buy more.

Compression usually results in artifacts and/or a slight noise increase/drop in DR. Beyond that, a compressed RAW file acts EXACTLY the same as a lossless/uncompressed RAW file. You can do EXACTLY the same things with it, because it's still a 100% RAW file. Just move the NR slider over a little more. ;)

You loose skin cells every time you rub your hands together, but it does not seem to bother you. We loose things everyday that have not practical value. The conclusion of this analysis was that there is no NOTICABLE loss in image quality. Why is this so hard to understand?

@Ebrahim - "So you guys want either highest setting RAW or crappy Jpegs?" - yep. It's not a big deal. The whole space argument is strange. You can afford a $600 camera and a computer, certainly you can afford some storage.

@stevo23 "The whole space argument is strange."Think of: Writing the compressed files to a second slower/smaller card in your camera as backup.Clearing the buffer faster to the card, having more images in the buffer.Using an iPad with limited space as the backup while traveling.Storing and processing huge amounts of files.

@Joe - putting it that way makes more sense, but there's no backup card in this camera is there? And would this really clear the buffer much faster? I see the iPad argument, but the other points aren't clear to me.

@BaldCol - LOL. I'm not a hater of compressed raw, even visually lossless compressed raw as it were. But the sample images above leave me wondering if this particular implementation is really worth it.

That's fair enough. Seems like Canon in an effort to develop less ridiculous mirrorless has discovered the need for a new compression format to explore fast fps and some other stuff. However, people should remember that this is not a new thing and that images are not like gas and as such cannot be compressed without some info loss.

I shoot RAW because I want to maximise data capture and postpone a lot of decisions, since I usually don't have much time when shooting. With RAW I "just" need to nail exposure and composition, but I don't need to nail WB, contrast, saturation, sharpness etc.

To compromise on the amount of data captured, it becomes suboptimal for its intended purpose.

To the commenters below: comparing a jpeg to an "unprocessed" RAW (except for the fact that talking about "unprocessed" RAWs probably means you have never seen one - without even a contrast curve, I mean) is like comparing a roasted chicken from the corner's deli shop to a raw one from the butcher. The latter you have to cook it yourself.

When I want to crop and shoot very high ISO I go 30mp Jpegs to have that huge room for noise reduction and oversampling but that's quite rare since the 5D produces wonderful images in 1920x1280 Jpegs at 30.000 ISO, with NR turned to high all croma noise is gone and just film-like grain in maintained.

How do you guys cope with shooting raw 30-50mp ALL THE TIME and processing each single file?!

16 MP is the sweetspot for me ATM, but it will look very good on a 4K TV some years in the future as well.

Properly pocessing RAWs is not all that difficult, after some years of experience and a good understanding of the underlying physics, the software(s) and having clear in your mind what you want to achieve from the moment you shoot.

Computers and storage are cheap. I shoot JPEG + RAW... keep the JPEGS that are good out of the box, keep the RAW files I want to process later, delete the rest. I have various 4k screens and an A2 capable printer... 2MP on anything bigger than a laptop looks terrible.

You don't need to nail WB, contrast, sharpness etc with JPEG either. Use automatic WB and you are already 99% in the ballpark, you can easily do the tiny correction without anykind trouble.

Contrast and sharpness is possible to tweak later even with JPEG. The JPEG real limitation is you don't get 4-5 stops shadow recovery, only 2-3 stops. And you can't get more than 1/3-1/2 stop highlight recovery while with raw you get 1-2 stops.

Thing is, Adobe's DNG compression seems very harsh. I see a lot of artifacting on anything I've tried compressing. Not worth losing that much detail. Never had that kind of issue on any camera that shot compressed.

The lossy compression in DNG uses a best-quality JPEG compression with special tone curves and meta data. It gives you RAW-like options with JPEG size files.

I played around with it once and found it amazingly good. I could hardly see any differences to the real RAW, even after extreme processing. I wish my camera would support it, for the „not so important“ stuff.

"the files will be 30-40% smaller than their losslessly compressed equivalents without any reduction in resolution."

Of course there will be some IQ penalty, because you don't get anything for free. It's nice to have this option, though, isn't it? Just use any of the other raw file options, if the new option doesn't suit your tastes.

Because on their equivalent cam Sony doesn't even give you this option as you have to use their compressed raws and you can see the artifacts next to highlights even pushing by 1 stop. You don't see people calling the A6000, A6300 and A6500 evil though.

Also, the A6000 had much more compression artifacts than the A6xxx cameras that followed. Even in 14-bit, which has more data to compress. You can see this in the studio tests. On the bright side, it doesn't affect all highlights. Only some that are on high contrast transitions, like specular highlights.

I have no idea how these files are written or compressed, but I can conceive of ways information can be compressed without losing anything. Take the series 3 3 3 3 and write it as 3x4. Or take a series of 50 characters and write it as abc, as long as the software reading it knows that abc is those 50 characters, you haven't lost anything.

I could see the difference immediately on zooming in to these comparison jpg's (!). But some people listen to lossy compressed music (AAC, MP3, MP4, etc.) and can't hear that it is, and others won't mind lossy compression here either, since they don't see or notice the difference. The choice for everyone is in the trade-offs.

Some here are a bit confused with names. Canon's first RAW format was CRW. This was replaced by CR2. Some cameras have smaller version of the RAW called MRAW ans SRAW. M and S versions had reduced pixel dimensions. For example for 5DsR, 'normal' RAW is 8688x5792, MRAW 6480x4320 and SRAW 4320x2880. With M50 Canon has replaced CR2 with CR3. Canon is calling it the next generation RAW format. In this format one has the option of 'normal' RAW as in CR2. But one also has the option of C-RAW or compact RAW. C-RAW replaces M and SRAW. C-RAW file size is 30 to 40% smaller than 'normal' RAW, but unlike previous MRAW and SRAW files, pixel dimensions remain same as usual RAW files. So, with M50 and CR3 one has the option of shooting 'normal' RAW or C-RAW.

Does this mean that Canon has developed something that is good? I'm not trying to be snarky, but this seems like a positive option that as of now is unique to Canon. If I'm correct there, this is some modicum of encouraging news from that company.

@BlueBomberTurbo The disdain was due to Sony offering nothing but lossy compressed RAW, followed by Sony offering nothing but lossy compressed or uncompressed huge RAW. If they had offered lossy compressed RAW as an OPTION to lossless compressed RAW, as Canon is doing here, there would have been zero disdain.

but less obviousis Canon in-camera raw post-processing via "touchscreen-sliders"much like sliders used to pp raw in mobile apps (Snapseed and Lightroom)

so, this added flexibility of "raw pp in-camera" introduces raw advantages to "shoot-raw-n-share-now" market, of which many smartphone users are discovering already, but are otherwise forced to do all raw pp "offline on some other computer"

no one here shooting raw, can fault Canon for nurturing potential of new "mobile raw shooting" in entry-level camera buyers, which DEMAND file compactness albeit with quality trade-offs of "lossy" MORE compact raw for 24mp full-resolution images

just because something is "lossy" (raw or jpeg) does NOT mean "extra time compressing it"but rather, a "simpler (smart) data read" that has less info, not "repackaged smaller"

"Older Canon's that used the CR2 file format could capture either uncompressed Raw files or 'medium' or 'small' equivalents, which saved you disk space at the expense of reducing resolution."

Wrong, wrong, WRONG! And in a much worse way that the plural of Canon, "Canons", is written without an apostrophe!

CR2 files are definitely compressed. In a lossless way, like a zip file, where you can retract every bit of original information. If CR2 files weren't compressed, why would file size depend on the contents/complexity of the scene? The whole premise of this article is deeply flawed.

Carey Rose, Jeff Keller, I respect you, but this time you have made a REALLY huge mistake. Please retract this article, as it is so fundamentally incorrect to begin with!

Does the paradox of your complaining in your second paragraph about a missing apostrophe then using "retract" instead of "extract" in your third derive from a lossy compression algorithm being applied to your comment?

You are correct, and we've fixed the errors. Most / all Nikon and Canon cameras use lossless compression by default. In fact, you can't even shoot uncompressed Raw on Canon and most Nikon DSLRs, with higher end Nikon DSLRs (D800 series and above) being the exception.

This is of course sensible; fully uncompressed Raws don't offer any advantage to photographers.

On top of the lossless compressed Raw Canon and Nikon typically use, Nikon also offers an additional 'visually lossless' compressed Raw, which uses a LUT to more efficiently encode values, as every step does not need to be recorded due to shot noise. This saves you a bit more space, but not as much as the LZW (or what have you) type compression enabled by default in 'lossless compressed'.

You still have the choice to use CR2 if you wish, but CR3 will increase the number of shots you can take before the buffer fills, enable faster burst speeds, and speed up rendering and other aspects of image editing, with a deterioration in IQ that is only visible in the most extreme cases of underexposure.

Also it will enable a major increase in megapixel counts of future cameras, because in-camera processing will be quicker, and I strongly suspect that is the major reason for it's development, as Canon have a 120MP camera in the pipeline.

It may not be right for you Ian, but thousands of Canon users will welcome this development, and those who still want CR2 will have the option to select it in preference via the camera menu if they wish.

entoman, the in camera processing won't be quicker. It's the opposite. The more you need to compress, the longer it takes and the more demanding for the processor it becomes. In the pipeline it will only save time if the time compressing is compensated by the faster time saving to the card.

It would be very revealing, if dpr conducted a comparison test with the M50, to see what differences (if any) there are between CR3 and CR2 regarding overall "compress and write to card" times, and what effect (if any) using CR3 has on buffer depth and burst speeds.

I'm pretty damn sure that Canon wouldn't go to the lengths of developing and introducing this new CR3 format unless there were considerable benefits to it, that may not be immediately apparent.

@entoman @PAntunescompression algorithms only become slower if lossless. This algorithm however, is rather simplistic and removes shot noise bits from the pixel values, then appying the same lossless compression to the remainders. It is actually faster.

More sophisticated lossy compression exists which leaves no measurable way to distinguish between the original and compression (in a blind test). But this isn‘t one.

@entoman, I understand what you're saying, but that's assuming that storage won't keep up with the megapixels. So far Moore's Law has mostly held and if anything, storage appears to be ahead of the megapixels. Also, the buffer issue is generally a design limitation and one that is becoming less of an issue. Besides, if someone needs to machine gun that much, perhaps her or she needs to reconsider their shooting style.

If there are other advantages to CR3 and it supports a new or better lossless compression algorithm, that's great, but based on what DPR has shared, I still feel that it's a mostly or entirely pointless development.

@lanIt certainly is "a mostly or entirely pointless development" to store all the shot noise that carries zero information (and is an incompressible fraction for lossless compression). But it has to be done right, and so far, all lossy raw compressors discard more than just shot noise. Still, it is no rocket science to do it right ...

Ian - "if someone needs to machine gun that much, perhaps her or she needs to reconsider their shooting style."

In a lot of cases I'd totally agree, but for sports or wildlife photography, a fast burst rate is essential. I photograph wildlife and BIF, and in these shots catching the legs or wings in the "right" position is virtually impossible without the benefits of a high burst speed.

Birds and animals move rapidly (as do atheletes etc) and at the max 7fs of my 5DMkiv I very often miss the exact moment when everything is in the perfect position. I sometimes hire a 1Dxii which shoots at 14fps and even that isn't always fast enough.

*IF* CR3 enables future cameras to shoot RAW at faster speeds then for me it is a good thing.

@entoman, I shoot sports and wildlife as well and find that I miss shots with my 1D X because even 10 or 12fps isn't enough sometimes. It's usually the frame rate that limits me vs. the number of frames, though. It's not to say that there aren't times when you hit the buffer and miss a shot as most cameras are too slow and have too small of buffers (I haven't always used a pro camera). Things have really improved since the early digital days, when you'd get 1-2 frames a minute, though!

@falconeyes - I think you'd be better off shooting JPEGs than this format, at least from what we know about it. If you know what you're doing, like pro sports shooters do, JPEGs work just fine for these kinds of purposes. For everyone else, RAW offers every other advantage outside of size/speed. The CR3 just seems to be an unwelcome compromise unless you always shoot well-exposed photos that just need more corrections and better white balance handling than JPEGs tolerate.

Ian - Yes I'd agree that it is burst speed more than burst duration that is key, but really we need both.

Often it is necessary or desirable to shoot several burst sequences in quick succession, and in these instances faster in-camera processing and reduced file size would prevent the buffer from filling so quickly.

Hopefully CR3 in combination with faster processors and better algorithms will help, and will still be a lot better than resorting to JPEG shooting.

Barney: They claim that CR2 isn't compressed right at the beginning of the article. This is simple and plainly WRONG. CR2 files ARE compressed, why else would each and every file be of different size? Please, see to it that this deeply flawed article is retracted!

Henrik: the CR2-files contain at least one JPG, so even if the RAW-data was stored uncompressed the file sizes would change between files. tested years ago with Nikons who offer uncompressed RAW files (something i don't understand why).

A BIG THANKS to DPR for bringing this issue to the table for analysis !

I had wished that this be discussed and had even spelt out my thoughts at the comments section of M50 sample gallery .I am delighted that the topic is generating so much interest & discussion ....regards

Except that the whole article is WRONG to begin with. CR2 files, just as CRW files before them, have always been compressed. Claiming CR3 files are the first ones to be compressed is simply and plainly WRONG. And with that, the whole article is irrecoverably (sp?) flawed, misleading, incorrect, wrong, wrong, wrong.

Carey: The premise of the article is also broken. As opposed to what this article claims at its very beginning, CR2 files are definitely compressed. That's one of the beautiful things of the (CRW and) CR2 format(s): because they are compressed losslessly way, they are smaller than dumb uncompressed raw files.

The most important thing to note here is that you have a choice. The M50 (and presumably all future Canon cameras) gives you the choice between enabling compressed CR3, or default uncompressed CR2 files.

I would imagine that after a few iterations, the CR3 option, if it proves popular, will become the default setting, but that we'll still be able to opt for CR2 if we wish. Also it's almost guaranteed that if you have a (future) Canon with twin card slots, that you'll be able to save CR2 to one card, and CR3 (or JPEG) to the other.

CR3 will save storage space, speed up write-to-card times and enable more prolonged bursts as the buffer will take longer to fill. It will probably also enable faster burst speeds than CR2.

Another major advantage is that during post processing, files will render and import/export faster, improving workflow.

I hope you're correct on the subject of this being optional longer term.

More complex compression routines usually require *more* processing; so you may find that the buffer clears more slowly as the camera's processor becomes the bottleneck (rather than the card), and/or burst rates may deteriorate as the camera has to do more processing on each shot.

On the basis that Canon have launched this along with DIGIC 8, I assume that the camera probably will be able to process this efficiently in hardware, but it may yet have battery life (or other) implications at the camera end.

It's also possible that your computer may not be optimised for decoding these images, so you may find processing slower rather than faster - yes, they'll come off the card quicker, but you may find that each file take longer to open in your editing software.

At the end of the day, there's (usually) no such thing as a free lunch!

There is no such thing as "uncompressed CR2 files". Have a look at two CR2 files: are they the same size or of different sizes? Yes, right, they are differently sized. How could that be if they weren't compressed?

Henrik - I wouldn't mind betting that if you compare differently exposed RAW frames from any brand, that the file sizes will differ.

I think you might be looking at "compression" the wrong way. Just because a file is compressed, it does NOT follow that any information is lost. The compression is lossless.

Compression in the case of CR2 retains all the data by using tables, rather than by "itemising" the data of each pixel individually. So the fewer the number of tones in an image, the lower the file size will be.

Everyone is reading more into the article than it says. CR2 is not lossy at full resolution, CR3 they are analyzing what is going on with the lossy compression.

What the article implies is that CR2, when set to medium or small, some kind of information loss is happening because it's hardly the full sensor data when your output file resolution is lower than the sensor's native resolution.

Maybe it is like Sony compression. I use sony 7-11 compression on the original a7 (they didn't update it for this model). Looks fine to me, but if I compared it to nikon d750 or d600 it is more noisier in low light/ high iso for sure. All relative to what you are used to. For beginner I doubt they care.

Canon has used losslessly compressed RAW forever, or at least since my first DSLR, the 5D in 2005. Lossless compression is beautiful in that it takes advantage of redundancy in the original information so that it can (almost always) make files smaller, but still reconstruct the original information bit-by-bit, hence the word lossless. Just like if you zip a text file: you lose 50-80% of the file size, yet you can restore every character of text without losing a single bit of data.

I don't think they ever explicitly say "lossless", but do mention compressed vs. uncompressed, so maybe people are getting compression and lossy/lossless confused. You can have a compressed lossless file; you can also have a compressed lossy file; and then there is the uncompressed (lossless) file. As mentioned above, Canon (as well as NIkon and possibly others) have done this and have both compressed lossless and lossy file formats. DPR is just comparing the compression function and its impact on IQ. I'm sure the title is a bit misleading.

The article currently states "Older Canon's [sic] that used the CR2 file format could capture either uncompressed Raw files or 'medium' or 'small' equivalents, which saved you disk space at the expense of reducing resolution.

However, if you enable the compact 'C-Raw' option on the M50, the files will be 30-40% smaller than their uncompressed equivalents without any reduction in resolution."

Compressed can be lossy or lossless, but uncompressed = lossless.

I would love to see a comparison of uncompressed v. lossless compressed v. lossy compressed at full resolution, if possible.

@matthew saville: From the article:"Older Canon's that used the CR2 file format could capture either uncompressed Raw files or 'medium' or 'small' equivalents"

What I'm saying is this statement is wrong. Up until this point Canon have used CR2, which is a *lossless* compressed RAW format.

The new CR3 format appears to be a *lossy* compressed RAW format, which you can see from the pushed shadows example DPReview posted - note the clumpy grain structure, indicative of lossy compression (in fact it looks like JPEG artifacting).

Here's a teardown of the CR2 format:http://lclevy.free.fr/cr2/If you look the RAW image data in a CR2 is stored as JPEG *lossless* data.

Uncompressed VS loessless is a non-sequitur, as another commenter already pointed out. Your point is pedantic. But, thank you for clarifying it; I too misunderstood the original point. (I wouldn't have even bothered replying if I had understood.)

I've been using raw compression (as well as 12-bit raw) on Nikon DSLRs for over 10 years now, and for extremely high-volume jobs where I /barely/ require the image editing that raw offers over JPG, ...it is a huge space-saver, often saving 30-40-50% in file size compared to a 14-bit lossless file. I even have plenty of low-ISO NEF files that are /smaller/ than many of my same-resolution high-ISO JPG files. Yup!

Don't get me wrong, I'm glad to see Canon is finally going down this road. They'll probably get it much better in 1-2 generations. Just like how Nikon failed at mRAW sRAW the first go-round in the D810, but is doing better now with the D850. (Party like it's 200...6?)

But as usual, no mention of the competing brand's options, or the fact that they've been around for over a decade. Thus, queue the Canon fans praising Canon for this "ingenious idea" lol...

@Sharlin, yes, and it was utterly useless at first, with even worse dynamic range than the already terrible full-res files, and barely any space savings compared to the resolution loss. Nikon's raw options had me laughing at Canon's raw options for years. I wouldn't have traded bitrate and compression options for size options, ever.

Like I said, I'm happy Canon is going down this road. It's about time, since Nikon is finally getting down the road of reduced resolution files, and doing a decent job of it allegedly in the D850.

My comment was mainly just to point out that articles like these seem to never mention when a competing product has had the same "exciting new feature" for over a decade...

As a Canon user, I fully agree with matthew saville that Nikon were there first. It hardly matters - it's extremely rare for Canon owners to switch to Nikon, or vice versa. What is important is that Canon now offers the option, and it's pretty feeble to criticise them for providing it, however late.

Sony was not smart for going straight from their "ambiguous raw" format to "totally un-compressed". It's unnecessary if you know how to do lossless compression in a truly lossless way, like Canon and Nikon do.

@ entoman, it sure as heck wasn't "extremely rare" when the D700 made a laughing stock out of the original 5D, and even the 5D2 for non-video shooters. Same with the D800 / D800e. The portrait & wedding shooters jumped ship in droves to the D700, and the landscape photographers dumped their 5D2's in droves for the D800e.

Not so much lately of course, since the playing field is finally leveling off, but it was a pretty shameful decade for Canon, depending on what you needed in a less-than-flagship camera.

BTW, again I wasn't criticising Canon for CR3, just rolling my eyes at the inevitable praises that will arise from Canon fans acting like this is the greatest thing ever.

By the way, this is not the 1st time this type of "better late than never" thing has happened.

matthew - Well, I have no intention of being drawn into a silly my-brand-is-better-then-your-brand debacle. Not my thing.

Unlike many, I can see the good points and the bad points in any system, and have no need to justify my purchasing decisions by deriding the choices of others.

I'm extremely happy with my cameras, which are near-perfect for my fields of photography, and I'm glad you are equally happy with your gear, and that others are happy with their gear. It's called being adult.

Indeed I too, unlike many, can tell a good decade and a bad decade when I see one, in any system, (let me know if you need me to "bash" Nikon a bit too) ...and I have no need to justify my purchasing decisions by deriding the choices of others.

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